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Subterranean homes are considered one of the most eco-friendly type of home designs. A home like this requires fewer raw building materials and is more energy-efficient, as the surrounding earth insulates the home, helping to maintain a consistent temperature year-round. The earth also provides protection from natural disasters such as wildfires, hurricanes, tornadoes and earthquakes. Although an earth-sheltered home has numerous advantages, if the home is not properly designed and built, serious problems can arise that are complicated, difficult and expensive to fix. Thorough research and working with an experienced earth-sheltered home builder can help you avoid costly mistakes.

Start with the Right Location

Subterranean homes can be found all over the world. The climate in any region, however, will play a key role in choosing the right building materials and design. Areas with high humidity pose some of the biggest risks with underground homes. Warm temperatures can cause condensation on interior walls. Excessive moisture can also lead to further problems such as mold and mildew. Dry climates with significant temperature extremes typically make ideal locations for underground homes. Granular soils such as sand and gravel provide the best drainage. A home built into a south-facing slope can be heated through direct sunlight coming in the southern-exposed windows, which is perfect for a colder climate. In a region with hot summers and mild winters, the home might benefit more in a north-facing slope, depending on the materials used.

Coverage Levels

Earth-sheltered homes can be built almost entirely underground, with very little of the structure visible above the earth, or the structure can be only partially covered. A partially covered home is called a bermed house. One elevation of the house is exposed and the other three sides are protected underground. The structural designs between a true subterranean and bermed house vary. But each benefits from the consistent temperature and insulation of the surrounding earth, and both should have energy-efficient floorplans.

Underground Homes

An underground home must be designed to withstand the pressure and moisture of the surrounding ground. The square and rectangular shapes of conventional houses aren’t practical with tons of earth bearing down from above. The curved walls of a dome are better suited for an underground dwelling. Atrium and courtyard designs can provide an open feeling, with the living spaces surrounding a central courtyard. Light and heat can enter through skylights in domes or through walls of glass facing the courtyard. Concrete is the preferred material for most builders, who apply it over a framework of steel beams and rebar. In addition to soil that has good drainage properties, installed drainage systems should also be in place to draw water away from the structure. Additional waterproofing is also needed.

Bermed Homes

The front face of a bermed home typically faces south to take advantage of solar energy for heat and light. The home can be built into an existing slope in the ground, or earth can be filled in around three sides of the home. The most heavily used living areas share the light and heat from the exposed facade, and skylights are installed wherever possible. In many bermed home designs, the roof is also covered with earth for added insulation, fewer building materials such as roof tiles and rain gutters and less exterior maintenance. Concrete is still the main building material used on the underground portions of the home.

Waterproofing Methods

Groundwater is one of the biggest hazards for a subterranean home. It’s important to ask your builder what type of waterproofing method will be used to protect your home from groundwater. Common materials used to waterproof underground homes include liquid polyurethanes, plastic and vulcanized sheets, rubberized asphalt and bentonite. Climate or weather conditions may also affect the type of waterproofing method used. For example, liquid polyurethanes require dry, relatively warm conditions. Bentonite is a material made from clay that expands when moistened, forming a waterproof seal. It can be made into panels or sprayed onto the walls. Rubberized asphalt sheets, plastic and vulcanized sheets must be sealed properly to avoid leakage between the sheets.

Alternative Sustainable Designs

Some builders come up with creative ways to repurpose and reuse building materials, such as Earthship creator Michael Reynolds, who designs green homes using old tires. If you want to eliminate the materials that are not eco-friendly, such as concrete, from an earth-sheltered home and design a completely sustainable green home, use such green technology and principles to design your earth-sheltered home. The walls of the home are made from old tires packed on the inside and surrounded with earth and stacked like bricks, creating a durable, load-bearing wall that doesn’t require a concrete foundation underneath. More earth is added behind the tire walls, creating a thermal fortress around the home. Interior walls are made from recycled materials such as aluminum cans and plastic bottles. Solar and thermal energy is used to cool and heat the home, which also has self-sustaining systems in place for water, sewage and even food production, allowing homeowners to live completely independent of public utilities and fossil fuels.

About the Author

Michelle Radcliff owned a retail home furnishings business for eight years. Radcliff offers decorating advice on her blog, Home Decorating News, is a regular contributor on interior design at LoveToKnow.com and earned certification as an interior decorator from Penn Foster College in 2013.